1. Technical Field
The invention relates generally to a method and apparatus for retrieving and locating tie plates on a railroad tie. More particularly, the invention relates to a machine capable of picking up tie plates and positioning them on a railroad tie. Specifically, the invention relates to a machine capable of traveling down railroad rails and precisely placing tie plates on railroad ties at high speed.
2. Background Information
Construction and repair of railroad tracks can be a cumbersome and difficult process due to the remote locations and various terrain that must be traveled on. When a portion of the railroad track needs a new rail or the railroad ties must be replaced, the tie plates are removed and a new railroad tie may be utilized. However, the original tie may be suitable if it is not worn.
A tie plate is required on each side of a tie to hold the rail and as many as 3,000 tie plates are required for only one mile of track. Further, tie plates can weigh up to 34 pounds each and must be precisely placed on the railroad tie in order to facilitate rail replacement. Therefore, it is unreasonable to expect a laborer to lift a 30 pound tie plate and precisely place 3,000 tie plates in an efficient and effective manner.
A number of prior machines have been used to locate tie plates on railroad ties using a variety of methods. Some of these methods use magnets to travel over the railroad tie plates resting on the railroad ties after the rail has been removed to pick up the plates and dispose of them accordingly. Still other machines use magnets on a drum to locate the tie plate as the drum rotates during forward movement of the machine. These second machines utilize a stop-and-go methodology wherein the device stops in order to permit the tie plate to be released during operation.